Airborne Dilemma: An Update

Airborne transmission of the coronavirus that causes COVID-19 is problematic because it means the virus may be transmitted without close contact. In its most straightforward interpretation, airborne transmission refers to the ability of a virus to be spread by droplets small enough to be suspended in the air or airborne. While larger droplets quickly drop to the ground, droplets less than 5 micrometers (
m) in size, generally called aerosols, linger in the air for hours and can be moved by air currents such as those created by the air conditioner. Respiratory droplets produced during exhalation (e.g., breathing or speaking) can emit aerosols containing the influenza virus at as many as ten particles per second. Airborne viral particles travel further and are more communicable regardless of whether a mask is worn. COVID-19 is no longer a pandemic. Mutation, antiviral therapy, vaccinations, and herd immunity have reduced its virulence. Yet, immunosuppressed patients, such as those who have received organ transplantation or those who are chronically ill, are still at risk of acquiring COVID-19 and may have a severe course. Precautions should be exercised when encountering them.